1. Field of the Invention
The present invention relates to a toner supply control system and method for an image forming apparatus having a development unit using a two-component developing agent.
2. Description of the Background Art
When image forming apparatuses form images using a developing agent having toner therein, it is important to maintain the toner concentration at a given level or range in a development unit to form images with high quality consistently.
The toner supply operation for image forming apparatuses can be mainly determined by two factors: image information to be output and environmental conditions. The image information such as print information directly relates to the toner amount to be consumed when outputting images, and the toner supply operation can be conducted with high precision in view of the output image information. However, because the toner is composed of powder particles, it is difficult to supply an exact amount of toner when supplying the toner. Further, the toner supply amount may fluctuate from one apparatus to another. Environmental conditions information such as temperature, humidity, and user settings need to be considered to secure the desired image quality, in which a toner sensor can be used to detect the toner concentration in a developing agent, and the toner supply operation can be conducted in view of a detection result of the toner sensor.
Conventional approaches employing feedback (FB) control or a combination of FB and feed forward (FF) control to compute the appropriate toner replenishment amount based on the output image information, although generally successful, either fail to effectively maintain the toner concentration at the proper level due to lack of a toner concentration sensor or have problems adjusting the timing of the delivery of replenished toner.
Moreover, although the toner supply operation can be conducted when the output image information is used for computing the toner supply amount because the output image information directly relates to the toner amount to be consumed by an image forming operation, and the toner consumption amount can be effectively computed with a higher precision compared to toner concentration detection by the toner concentration detector, the toner supply operation needs to be conducted more precisely.